.\" Copyright (c) 2020 Yubico AB. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are
.\" met:
.\"
.\"    1. Redistributions of source code must retain the above copyright
.\"       notice, this list of conditions and the following disclaimer.
.\"    2. Redistributions in binary form must reproduce the above copyright
.\"       notice, this list of conditions and the following disclaimer in
.\"       the documentation and/or other materials provided with the
.\"       distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
.\" "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
.\" LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
.\" A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
.\" HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
.\" LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
.\" OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.Dd $Mdocdate: August 5 2020 $
.Dt FIDO_DEV_GET_TOUCH_BEGIN 3
.Os
.Sh NAME
.Nm fido_dev_get_touch_begin ,
.Nm fido_dev_get_touch_status
.Nd asynchronously wait for touch on a FIDO2 authenticator
.Sh SYNOPSIS
.In fido.h
.Ft int
.Fn fido_dev_get_touch_begin "fido_dev_t *dev"
.Ft int
.Fn fido_dev_get_touch_status "fido_dev_t *dev" "int *touched" "int ms"
.Sh DESCRIPTION
The functions described in this page allow an application to
asynchronously wait for touch on a FIDO2 authenticator.
This is useful when multiple authenticators are present and
the application needs to know which one to use.
.Pp
The
.Fn fido_dev_get_touch_begin
function initiates a touch request on
.Fa dev .
.Pp
The
.Fn fido_dev_get_touch_status
function continues an ongoing touch request on
.Fa dev ,
blocking up to
.Fa ms
milliseconds.
On success,
.Fa touched
will be updated to reflect the touch request status.
If
.Fa touched
is 1, the device was touched, and the touch request is
terminated.
If
.Fa touched
is 0, the application may call
.Fn fido_dev_get_touch_status
to continue the touch request, or
.Fn fido_dev_cancel
to terminate it.
.Sh RETURN VALUES
The error codes returned by
.Fn fido_dev_get_touch_begin
and
.Fn fido_dev_get_touch_status
are defined in
.In fido/err.h .
On success,
.Dv FIDO_OK
is returned.
.Sh EXAMPLES
Please refer to
.Em examples/select.c
in
.Em libfido2's
source tree.
.Sh SEE ALSO
.Xr fido_dev_cancel 3
.Sh CAVEATS
The
.Fn fido_dev_get_touch_status
function will cause a command to be transmitted to U2F
authenticators.
These transmissions should not exceed a frequency of 5Hz.
